Even if you don’t know your exact rank, what would you estimate? Top 5% 10%? 20%? 50%? Bottom 50%?
At some schools, a 3.6UW GPA might be in the top 50%. At other schools, if there is less grade inflation, it might be higher. Having some sense of how you compare with your peers is part of the analysis of schools with competitive admissions.
Additionally, how does the rigor of your coursework compare with the courses that have been offered at your school? Are you taking all or nearly all of the AP classes available? Or will you end up not taking a number of them? Again, this comparison of what you’ve done compared to what was available to you will be part of the review process in the college admissions’ offices.